Although some people are more Internal (belief in personal control of destiny) while others are more External (belief in fate controlling destiny), the locus of control does change as a person ages. Children are more likely to be External, as their well-being depends more on others; children believe that their destiny is regulated and controlled by adults, and only slowly lose that belief as they grow older and more independent. Interestingly, many children develop magical thinking, in which they believe that their actions have a direct effect on events; this would be an example of early internality.

...as children grow older, their locus of control tends to become more internal; internality becomes stable in middle age and does not diminish in old age...(Engler, Personality Theories: An Introduction, Google Books)

This correlates internality with personal independence; as a person grows older, the effects of personal action on events become both more "real," as in actual instead of magical, and more obvious. People who work hard tend to associate their success to themselves; this increases internality, which reaches a certain point and remains there as the person ages. However, it is possible for people who have bad luck (entirely random) to start believing that they are incapable of changing their destined fate; this can lead to addiction or other problems.

The Locus of Control test developed by Rotter in 1966 assesses, in 13 different items, the personal expectations of the tester. The aim of the test, is to determine whether the tester uses his internal locus, or external factors, as the key elements of failure, or success. Normally, a low score (0-5, out of 13) relates to internal locus of control while a higher number points at external locus. There is no right or wrong answer, nor does a low number mean anything wrong. It simply works better for a counselor to identify the client's locus of control in order to direct the therapy session toward the right direction.

The test results of any cognitive and personality trait test do change as the individual develops cognitively, psychologically, emotionally, and socially. This is congruent with Albert Bandura (1960) and his Social Learning theory, which argues that the environment and the individual "cause" each other. The assumption is also valid with Erich Bronfenbrenner's Ecologycal Nesting Model which offers that individuals are molded by a system consisting on:

the microsystem- the immediate environment

the mesosystem- the combination of 2 microsystems interacting such as parents/community or family/school.

the exosystem- the outside environment that still affects the individual (government, service departments)

the macrosystem- our world, at large.

The ideal scenario in any psychological setting is that these factors influence an individual and lead to maturity of thought and action in a manner which coincides with Erik Erikson's Psychosocial Stages of Development (1959). This latter theory expresses that the aim of each developmental stage of life is to achieve a goal that will help the individual to fully develop productively. This being said, the chances of the test results of a Locus of Control test will inevitably change from one stage to another.

As a result, experience will dictate whether the locus of control is, in fact, internal or external. Only through experience, as well as through developmental and cognitive change, is that we will understand exactly what "causes" us, as Bandura would argue.